import math
x1,y1,x2,y2=map(float,input().split())
a=(x2-x1)**2+(y2-y1)**2
l=math.sqrt(a)
print(f'{l:.8f}') import math math x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 a=(x2-x1)**2+(y2-y1)**2 a (x2-x1)**2+(y2-y1)**2 (x2-x1)**2 x2-x1 x2 x1 2 (y2-y1)**2 y2-y1 y2 y1 2 l=math.sqrt(a) l math.sqrt(a) math.sqrt math sqrt a print(f'{l:.8f}') print f'{l:.8f}' x2,y2=map(float,input().split()) map(float,input().split()) x2 x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1 a=(x2-x1)**2+(y2-y1)**2 (x2-x1)**2+(y2-y1)**2 a y2=map(float,input().split()) map(float,input().split()) y2 y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 l=math.sqrt(a) math.sqrt(a) l
import math
x1,y1,x2,y2=map(float,input().split())
a=(x2-x1)**2+(y2-y1)**2
l=math.sqrt(a)
print(f'{l:.8f}')
